Dental hand-engine.



W. G. SHELTON.

DENTAL HAND ENGINE.

PLxcATloN FILED APR. 4. |914.

Patented 09h17. 1916.

INVENTR this engine is a' combined radial UNITED sT.

WILLIAM GEI To lll whom 1' t may concern Applicatic Be it known that l. lYiLLLiii GExTnY Siii-zLrox. a citizen of the llnited States of America. residing in the borough of .Man-

liattan, city. county. and State of haveinvented `certain new and proveniente in Dental Handwliicl tlief'following is a specific N ew York, useful Imflngines, of ition.

This invention relates to dental handengines and has foi` an object t provide a compactfandwell balanced hand tool having an electric motor within i* and which rests securely in the hand of the operator,

and which the hand can hold and at the same time control wit Among the improved features e ball bearing for both shafts, bot

Ioinfortably h dexterity. Inbodied in and thrust h shafts extending to the back of the engine, one of which is mounted within the other and the being disin the presature shaft row or set t mentioned ring for the le, and in addition tothis serving as a transmission gear preferably 'of the reducti The invention also embodies 'in type between the said shaft and spindle. f

a normally open reversing switch for the electric motor,

such switch being capable upon the release of the finger piece by the operator of bringing the motor to rest. Upon e finger piece the operator can sta in either direction. The motor there are open to the operator tions of motor aetionfeforwarl igaging the rt the motor icing at rest two condidrive and ieverse, and lie can bring about either independently of .the other. switch or circuit closer` or in This reversing its function of bringing the motor to rest when the finger piece is released or the engine laid aside by tlieoperator. a circuit breaker.

is located at the rearof theengine. The switch is shown madev up annular in formand the coniiniitator. which is also l .rearof the engine. The pair lstituting the switch are spaced apart by suitf I able insulation blocks which act and; between siich rings are di resilient and ifriishir-srone of the rings being of siich forni and location rela surrounding icated at the f rings conas trunnions sposed the brushes that it normally engages both brushes and holds its companion ring out- Specifcation of Letters Patent.

tively to the iTEs PATENT OFFICE.

\TTRY SHELTON, OF NEW YORK, N. Y.

DENTAL HAND-ENGINE.

Patented Oct. 17, 1916.

n ledApril 4, 1914. l Serial No. 829,456.

of engagement with both brushes. The switch is shown controlled by a finger piece extending rforwardly of the iiiotor housing and having a portion disposed along the dental hand-piece which is shown of conventional construction and in position for the engagement of the finger of the hand supporting the engine.

An illustrative embodiment of the invention is shown in the drawings.

Figure 1 is a view partly in elevation and partly in central longitudinal section, the plane of such section being indicated by the line 1-1 in Fig. 3. Fig. 2 is an enlarged section of the rear of the device, the plane of such section being indicated by the line 2 2 in Fig. 3. Fig. 3 is partly a rear elevation and partly a section, taken transversely, the plane of such section being indicated by the line 3 3, Fig. Fig. 4 is a detail of the switch disassembled from the structure; and Fig. 5 is a perspective view of the switch and brushes on the scale of Fig. 1,

this view illustrating diagrammatically the circuit.

There is illustrated an engine or motorcasing 7 of convenient form to be held in the hand of the operator. Such casing carries a dental hand-piece 8 illustrated of conventional form. The shape and dimensions of the casing and the parts inclosed therein are such that the opt ator may hold the tool with facility and perform his operations with delicate dexterity. The motor is of light construction and wound and constructed for high speed, a speed in excess of that which is available for dental operations. The casing is shown formed in two parts, il and 10, overlapping at the central portion and provided with a recess for engaging the field windings and housing the lsaine. such windings being indicated by the reference character 11. A single fastening device for holding together the casing sections 9 and 10 and holding to these the ywindings is illustrated in the form of a screw 12. r1`he arn'iature 13 carried within the housingvor casing is shown provided at its rear end with a coinmutator ring 11. The armature shaft 15 is shown, of h'ollow or sleeve-like construction through 4which extends the driven shaft.- or spindle 1G, which portion 16 is shown' yhaving screwthreaded connectionwith the tool spindle 17 which' extends through the dental handpiece which is at the front of the engine.

The front end ot .the armature shaft and the front end of Vhe rlriven spindle 16 are shown provided with a thrust bearing 1S.

The practicability of this hand tool resides largely in the fact that lthe transmission gearings constitute a radial and thrust bearing for the driving and driven spindles and is located at the rear of the engine casing. The transmission gearing is formed after the analogy. of' a self-contained ball bearing comprising a single set'or series of balls. The inner bearing member or ring ot the ball bearing and transmission gear isillustrated at 19, and is shown secured to the armature shaft by means of a driven fit. The outer bearing .member or ringis illustrated at 20, between which rings there is shown a single series or set of balls 21. Each of the rings 19 and 20 is provided with a groove constituting the track for the set of balls. The balls are shown mounted in a suitable cage 22. The driven spindle 1G is shown extended' rearwardly of the casing and there provided with a clutch 23 for engaging the cage member 22. In the present illustration the vclutch is provided with a series of pins 24 entering suitable sockets or' recesses in the cage..

The back closure for the casing is illustrated at 25' and is shown having a screwthreaded connection with a rearward flange of the easing or housing member tl. The.

' back closure is provided with a socket for housing the ring 2O and has suflicient resiliency to hold such ring against rotation. By adjusting the back closure forwardly or backwardly upon its screw-thread, the amount of pressure of the balls upon the respective rings is adjusted, therebyl controlling theamount of slippage.

The .transmission gearing constitutes not only a transmission device but also, as it is stated above, a bearing for supporting both the driving and driven spindles or shafts at the rear end of the motor or engine-casing. In some instances it will be desirable to place a washer 26 between the clutch Q3 and the ring 19.

Brush holding caps 27 are shown having screw-threaded connections with the housing member 9. lVithin each of these caps and suitably insulated therefrom is a Ine-- tallic brush holder Q8. in which thev brush 29 is mounted and elastically pressed against the commutator. The current for operating the motor is preferably led in by means of a cable 30 at the portion of the housing which will be the normal lower position when the tool is in the hand of the operator.

The brush-holders in the switch herein illustrated vconstitute the Contact points cooperating with the contact p'oints of the movable member of the switch. Such movable switch member is shown comprising two rings 31 and mounted upon a pair of trunnion blocks 33 which are supported by suitable screws in the form of pivots 3l Icarried by the housing member 9. These blocks and pivot screws are shown quartering with the brushes. The relative location and form of the rings and brush-holders is such that the resiliency of the ring 31 will normally hold such ring in engagement with both brush-holders and at the same time will hold its companion ring 32 out ot engage: ment with both brush holders. The wires cated at the back of the engine and are lo-` cated adjacent the transmission gearing. A

suitable finger-piece 3T is shown extending d forwardly of the device and along the dental hand-piece in position for the engagement of the finger of the hand holding the tool. Thisfinger-piece projects backwardly through the casingpast the field-windings and armature and into position to be connected to the movable portion of the switch. The connection afforded is shown in the form` of a block 38 of insulation material suitabl)v secured to the ring 32 and having a pair of upstanding fingers engaging notches in the end 39 of the finger-piece. By this ineans the-movable member ot' the switch ina)v be moved either forwardly or backwardly from its normal position of rest for causing the motor and through it the driven spindle by means of the transmission gearing to rotate in the desired direction.

Although the foregoing` description embodies certain statements as to the operation of the device. the operation as a whole will be briefly described. Assuming that the cable 31 is connected with some suitable source of electrical supply and that the parts are in the position illustrated in Fig. 1, the

operator will take the tool in his .hand and place his finger upon the finger-piece 3T. lt is now in his power to start the rotation of the tool spindle at full speed in either direc` tion from .a bosition of rest which is effected by moving the finger-piece either forwardly or backward-ly as the case may be. A backward movement of t-he finger-piece will bring the movable switch members into the position illustrated in l"ig.':2, wherein thel ring 31 is engaged with one of the brushholders and the ring 32 is engaged with the other brush-holder. whereupon the armature will revolve and transmit b v means of' the ring 19 and balls '221 rotation to the cage i1",1'er`nberv '22 anfd 1vthroughthe clutc "a corrtirmationo ffthe tool'` spi idle which passe's'-fr0m its point o-feng'ageme t with vthe ltia'nsi'niss'iongearing iat: theirearof `Athe enring romilfotation the?4 cag'e' 'm nahen-22 is driven-or rotated .at a? reduced 'ra je of. speed 'ity of the m'otrfisreduc'edtoa workable-s eed.' 'The -r'eq'uired power-is had 'byj providing a' very high speed ligl 1 t\veightmotor a gearing this; down to?V the Workablefspeed It will be ap]`)arent `that the ilh strted example of the-invention. is'afpracicable em'- bodiment thereof suitableiforcer ain classes of work and that changes ofcnstruction mav be made withinthe terms of the claims without departing from the spiri' of the invent-ion. Y Y

lVhat- I claim is z 1. Ina dental engine hand too the combination with a casingand a moor therein, of a dental hand piece carried b the front of the casing at one sideof the motor, the motor being arranged adjacent the handpiece, an armature shaft anda tol spindle mounted one within the other an vextending tothe back of the casing at the o her side of ,the motor, and va ballbearinglcar iedl by the back of the casing and having o e member -attaehedto the shaft, the spindle being oonnected to another member of suel ball-bearing, lwhereby the said ball beari g supports the motor and affords a rediictiortransmission mechanism between the .shaft and spindle, said transmission mecha' of light weight relatively to th the motor.

2.111 a dentalengine hand tol, the combination 'with a Casing and aV mo or therein, of a. dental hand piece carried b the. front of the casing at one side ofthe motor, the motorbeing arranged adjacent the. handpiece, an armature shaft and a tol spindle mounted one within the other an extending tothe back of the casing a-t-.the oher side of the motor, and a combined radial and thrust ball bearing carried by the back of .the casing and having one member atta hed to the shaft, thespindle being connecter to another member of such ball bearing,\\liereb the said ball bearing supports thel motor and affords a reductiontransmission mechanism between theshaft and spindle, mission mechanism being of lijht weight relativel \Y to the weight of the motor.-

3. In a dental engine hand toil. the comhination with a casing and a moior therein. ofia dental hand piece carried b the front ism being weight of of the casing at one side of the motor. the

motor beingT arranged adjacent thc handpiece, an armature shaft and a tool spindle mounted one within the other am extending to the back of the easing at' the o .her side ot the m oto r,''and al reduction'transmission between theshafft4 andfspindle and.' comprising `-a ball bearing carriedfby' th'e'i'bacltiof the casing, means Lfor preventing "the ,rotation of one 4memherofsuch 'ball bearing. vanother member of the ball bearing beingattached to the sha-ft, and the 4spindle being connected. to a third inemberof `such .ball bearing. whereby the rsa'idffball bearing supports the i'nolior and. affords]laA reduction transmission mechanism' between theshaftand spindle,

' the jsaid'r'tra n smissfion: 'mechanism 'being' fof relatively to ;the .fweightVA of the tion with a dental hand piece, 'of a motor casing carried thereby, an armature mounted within the casing and provided with-av commutator ring at. the side opposite the hand piecet a reversing switch at the same side of the armature, and a switch actuator extending from suchv switch forwardly to the other side of the armature.

6. In a dental handengine the combination witha motor casing of a dental handpiece carried by the front side thereof, an armature mounted in said'casing and provided at the rear with a commutator ring, brush-holders mounted in the casing adjacentsaid armature ring, and a switch in the form of a pair of rings surrounding said armature ring and located upon the respective Sides of the brushes.

7. In a. dental hand-engine, the combination with a motor casing of a dental hand- -piece carried by the front side thereof, an' armature mounted in Said Casing andprovided at the vrear with va commutator ring, brush-holders mounted in the, casing adjacent said armature ring. and a switch 1n the form of a pair of rings surrounding said armature. ring and located upon the rc.- spective Sides of the brush-holders. one of said rings bcingresilient and normally bearing against said brush-holders and adapted to maintain the other ring out of engagement with both brushes, and means for tl e.\' ing said resilient ring for placing one ring into engagement with one brush-holder and the other ring into engagement with the other lu'nslrholdcr.

S. .ln a device ot the character specified` thil combination with a commutator ring of a .switch therefor,comprising a pair of brushv hohh-rs and a pair of ring"C surrounding thel cominntator ring an-.i oci upon the respective sides of the brush-holders, one ofy said switch rings being resilient and nor` mally bearing against said brush-holders and adapted to maintain the other ring out of engagement with both brushes, and means for flexing said resilient ring for placing one ring into engagement with one brushholder and the other ring into engagement with the other brush-holder. a Y

9. Inra dental hand-engine, the combination with a motor vcasing comprising two portions overlapping at their edges and' shaped at such overlapping to form a recess for housing the field winding, a dental handpiece carried by the Jfront of the casing, an

armature in said casingprovided with a` hollow shaft` a spindle dlsposed 1n the 1,201 ,ses

dental hand-piece and extending through said hollofw shaft to the baclg of the casing, the back ofthe casing being provided with a closure having screw-threaded engagement therewith, a transmission device after the analogy of a ball bearing, having the inner bearing member mounted on the armature shaft, the outer bearing member carried by the said closure, and a. clutch carried by the said spindle and engaging thevball cage.

In witness whereof, I have "hereunto signed my name in the lpresence of two sub-V scribing witnesses.

l/VILLIAM GENTRY SHELTON.

Witnesses:

CHAS. LYON-RUSSELL, GUsTAvE R. THoMPsoN. 

